In Japanese Unexamined Patent Application Publication No. H10-105239, a vehicle driving control system configured to control a vehicle when this vehicle merges from one travel lane (i.e., its current travel lane or a merge lane) into another travelling lane (hereinafter, referred to as a merging target lane) is disclosed. In the following description, a vehicle merging from one travel lane into a merging target lane is referred to as a merging vehicle.
This type of vehicle driving control system recognizes a position and a traveling condition of each of a merging vehicle (i.e., the own vehicle) and another vehicle. Then, on the basis of this recognition result, the vehicle driving control system controls the traveling condition of the merging vehicle such that the merging vehicle can merge from the current travel lane into the merging target lane without contacting another vehicle.
Depending on a peripheral situation at the beginning phase, a vehicle driving control system installed in a merging vehicle determines that this merging vehicle can merge from one travel lane into the merging target lane at the beginning phase and starts driving control of this merging vehicle. However, it becomes difficult for such a merging vehicle to merge into the merging target lane due to change in its peripheral situation after starting the driving control in some cases. Even in such cases, it is required to safely control the merging vehicle.